The present invention relates generally to swimming goggles for covering and protecting the eyes of a swimmer while enhancing the swimmer's vision. In particular this invention relates to swimming goggles that geometrically approximate a hydrodynamically streamlined profile with respect to the swimmer's head while simultaneously permitting standard vision when the swimmer's eyes are either above or below the water surface. More particularly, the invention relates to lens structures for swimming and diving goggles.
Swimming goggles, especially those for competitive swimmers, should provide several functions and exhibit several characteristics. Firstly, the goggles should protect the swimmer's eyes from the irritations of the water. In swimming pools these irritations are caused from chemical disinfectants such as chlorine, bromine, or ozone. Additional irritations are caused from incompatible pH levels, ionic concentrations, and chemical buffers in the pool water. Secondly, goggles should provide for standard vision both underwater and above water. Thirdly, the goggles should perform these functions without requiring the swimmer to alter his or her diving entry into the pool for fear of the goggles being displaced from the swimmer's head by hydrodynamic forces and moments. Fourthly, the goggles preferably exhibit no more hydrodynamic drag than if the swimmer were swimming without goggles. Prior art goggles have failed to satisfy all of these functions and characteristics.
Swimming goggles have been made to match a section of a hydrodynamically streamlined contour to the face. (For example, see FIG. 1.) Shaping goggles this way permits a swimmer to dive into the pool, turn and push off from walls, and swim with minimal concern that the goggles might be pulled off or pulled ajar due to hydrodynamic forces and moments. Additionally, the hydrodynamic drag of such goggles is less than that for coplanar lens swimming goggles, an advantage for competitive swimmers. The deficiency of these types of prior art goggles is that underwater binocular-like viewing is not standard. Incoming parallel rays diverge as they refract through the hydrodynamically streamlined lenses. (For example, see FIG. 2.) This requires that the swimmers eyes point in convergent directions to attain binocular focus while viewing underwater; the swimmer must adjust his or her eyes into a cross-eyed orientation to attain binocular vision. It is difficult to rapidly toggle back and forth from a cross-eyed orientation for underwater binocular viewing to a straight-ahead orientation for above water binocular viewing. Double images are observed when viewing underwater with both eyes looking straight ahead. Using these prior art goggles may cause headache, vertigo, or induce nausea.
To attain standard vision when wearing swimming goggles requires that parallel rays remain parallel when passing through the goggle lenses both above and below the water. Specifically, if two rays are parallel as they enter the lenses of the goggles with one ray passing through the left lens and on a trajectory to then intersect the center of rotation of left eye and the other ray passing through the right lens and on a trajectory to then intersect the center of rotation of the right eye, then they shall also be approximately parallel after both rays pass through the lenses of the goggles.
Keeping rays parallel as they pass through the left and right lenses of goggles has been accomplished in the prior art in several ways. One technique disclosed by Bengtson et al., U.S. Pat. No. 4,051,557, utilizes coplanar sections of plastic or glass as part of the left and right lenses. Widenor, U.S. Pat. No. 3,027,562, discloses a flat section of plastic in front of the eyes which then curves in the peripheral region of viewing outside of binocular vision. Another technique, disclosed by Hagan, U.S. Pat. No. 3,672,750, uses a section of a sphere as the outer surface of each uniform thickness lens with the center of radius of each sphere close to the center of rotation of each eye. Here, any ray which is on a trajectory to intersect the center of rotation of an eye and is within the field of view of that eye is normal to the lens surface. Flory, U.S. Pat. No. 5,313,671, discloses use of a section of a cylinder instead of a sphere. These techniques preclude matching the contour of the face with a goggle that is minimally intrusive into the free stream of water such as shown in FIG. 1.
Swimming goggles of the prior art may also add optical corrections similar to those found in corrective prescription glasses to reduce the effects of visual deficiencies such as myopia, hypermetropia, and astigmatism. For coplanar lenses these corrections are often added to each of the inner lens surfaces with the outer surface of each lens remaining flat. Most commonly offered are simple spherical corrections in whole or half diopter steps.
Reducing the tendency of standard vision goggles from being pulled off or ajar has been addressed by the prior art in several ways. Drew, U.S. Pat. No. 4,279,039, discloses attaching coplanar lens goggles directly to the swim cap. Van Atta et al., U.S. Pat. No. 7,475,435, discloses reducing coplanar lens size. Fukasaw, U.S. Pat. No. 6,996,857, discloses adding fillets to the protruding sections of coplanar lens goggles.
Prior art refinements enhancing standard vision include blackening whole sections of the viewing field as disclosed by Yokota, U.S. Pat. No. 7,165,837.